Weekly Activity bulletin of volcano Nevado del Ruiz:
Subject: activity level of the Nevado del Ruiz volcano.
Activity level Yellow or (III): changes in the behavior of volcanic activity.
Regarding the monitoring of the activity of the Nevado del Ruiz volcano, the SERVICIO Geologico COLOMBIANO through the OBSERVATORIO VULCANOLÓGICO Y SISMOLÓGICO OF MANIZALES, reports that:
During the last week, the volcanic system continued to present instability in his behavior. The recorded seismic activity was mainly associated with fluid dynamics in volcanic conduits. This seismic activity has been characterized by the recording of LP type earthquakes (long time) and episodes of volcanic tremor of short duration, but with significant energy levels. These have been primarily associated with gas emissions and ash into the atmosphere. Some pulses of tremor associated with ash emissions have been verified through the web cameras installed in the volcano area, as well as by officials in field mission in the area of influence of the volcanic structure.
Pulse of tremor at 4:33 p.m. were associated with observed emission of ash from the east and west of the volcano. This seismicity related to fluid circulation is mainly located in the Arenas crater and around it . The above mentioned processes are usually accompanied by thermal anomalies (another typical feature of active volcanoes) which can be monitored using satellite images provided by different organizations such as Mírová portal from Italian universities of Turin and Florence. The September 26, 2015, a large thermal anomaly in the vicinity of Arenas Crater confirming the instability of the volcano Nevado del Ruiz corroborated that the eruptive process continues to evolve.
Seismic activity associated with the fracturing of the rock in the volcanic structure is located near the Arenas crater and to the north of it, at depths between 7.5 and 1.3 kilometers. The maximum recorded was magnitude M1,1 (local magnitude), corresponding to an earthquake on September 22 at 10:27 (local time) at a depth of 4.0 kilometers, this earthquake was the most energetic of the last week. Continuous volcanic deformation show some changes.
The volcano continues to emit into the atmosphere of significant amounts of water vapor and gases, including sulfur dioxide (SO2). The column of gas, steam and ash reached a height of 2000 meters above the summit of the volcano. The direction of the dispersion of the column was in harmony with the wind regime, which remained mostly to north-west of the volcano.
The Colombian Geological Service through the Volcanological and Seismological Observatory of Manizales continued to lead the process of socialization of technical information with various stakeholders in risk management in the departments of Tolima and Caldas.
The Colombian Geological Survey wishes to clarify that the different stations that are part of the network segment of volcanic surveillance in northern Colombia, within which lies the Nevado del Ruiz volcano are fully operational. In recent months, has been considerably improved the existing instrumentation with the installation of new stations focused on the diagnosis of the activity of the monitored volcanoes.
While the volcano Nevado del Ruiz remains to this day a yellow level of activity, it is possible that additional changes occur in the behavior of volcanic activity, indicating greater system instability and may involve changes in activity level.
October 04, 2015. Nevado Del Ruiz, Colombie :
Photo : SGC ( 2012)